Are you fighting mites at present mate? My snake caught them from the substrate from the shop.
I tried hypoaspis first. they need substrate and humidity. I kept conditions right but (maybe it was me) they didnt work.
I just used frontline last week and all mites are gone- overnight.
Personally it was hard waiting the 3 weeks it takes for the hypos to kick in and watch my snake suffer in his infested substrate. his temperatment is still worse now.
I put a small tub of eco soil stuff in my viv and then put the hypoaspis mites in that, I needed to buy two lots in the end to get rid of the mites in my case.
I put them in left for three weeks then bleached the viv again before adding more in which I left for two weeks then no more mites:2thumb:
Frontline is a much quicker alternative though but I definitely wanted to the hypoaspis mites and in the end they worked fine
I am currently on my second batch of hypoaspsis too. They have some substrate in there (which I baked in the oven to kill any nasties) which I spray twice a day. My viv is 4x2 and I think that may be why just one batch isn't enough. I am keeping my fingers crossed they may have gone. If I have no luck this time I'll be sending for some Provent a mite which I have had success with in the past - just I want to get away from using chemicals this time.